demand同埋quantitiy demanded ge分別?!

demand=需求 (可以是無形的) eg. 我要買橙, 買橙=demand

quantity demanded= 有數量的需求、能量度的. eg. 我要買三個橙, 三個=quantity demanded

Damand is the ability and willingness to buy specific quantities of a good at alternative prices in a given time period, ceteris paribus.

Quantity Demanded is along a given demand curve, in response to price changes of that good.

quantity demanded 係在某一價格時, 消費者打算購買的數量。

demand 係消費者的購買計劃, 反映了價值與需求量的關係。
在一個 demand 中, 有多個 (價格+需求量) 的組合。